1. Field of the Invention
The present invention is directed to an improved process for reducing the agglomeration of finely divided alkali metal particles dispersed in an organic liquid and, more particularly, to a process for preparing finely divided sodium dispersed in an organic liquid using an aryl halide to prevent or reduce agglomeration of the dispersion.
2. Description of the Prior Art
Common methods for reducing particle settling and reagglomeration of alkali metal dispersions involve the use of a soap-types of material as set forth, for example, in U.S. Pat. No. 2,394,608 issued on Feb. 12, 1946.
A method for reducing or eliminating agglomeration of alkali metal dispersion in an inert organic liquid is disclosed in U.S. Pat. No. 2,579,257 issued on Dec. 18, 1951 and involves the use of two compounds which add together to form complex addition compounds that reduce or prevent agglomeration of dispersion. Compounds include alkali metal alkoxides and alkali metal organic compounds in which an alkali metal atom is directly attached to an allylic residue. Methanol and monochlorobenzene are disclosed as two compounds which react in the presence of sodium to form the addition product of sodium methylate with sodium phenyl which addition product is taught to decrease agglomeration.
U.S. Pat. No. 3,723,536 issued on Mar. 27, 1973 discloses a process for the synthesis of triaryl phosphines by reaction of an aryl halide with a phosphorus halide using a finely divided alkali metal which has been modified by the addition of either a triaryl phosphine and/or an aryl halide to control the rate of reaction and distribution of products. While chlorobenzene is disclosed as one of the possible additives, the patentees do not discuss the effect, if any, the addition of the aryl halide and/or the triaryl phosphine has on the condition of the particles in the sodium dispersion. The patentees teach that less than 5% by weight of either additive should be employed and preferably from 0.5-1% by weight because greater amounts, especially of the aryl halide, result in too vigorous a reaction and the formation of undesired by-products.
The process of the present invention is particularly applicable to the preparation of triarylboranes as disclosed in U.S. Pat. No. 4,046,815 issued on Sept. 6, 1977. This patent discloses the preparation of triarylboranes by reacting a finely divided alkali metal, an aryl halide and an orthoborate ester; contacting the reaction product with water to form the sodium hydroxide salt of a triarylborane and converting the salt to the borane.